The invention relates to a non-planar wing tip device for the wing of an aircraft, and to a wing comprising such a wing tip device.
From the state of the art non-planar wing tip devices are known which differ not only in their geometric shapes but also in their design sizes.
From DE 101 17 721 A1a wingtip extension for a wing is known, comprising an upper surface and a lower surface as well as a leading edge and a trailing edge, with the geometries of said wingtip extension being such that between a joint region for attachment to a wing and the tip of the wingtip extension a continuous increase in the local dihedral, a continuous increase in the sweep of both the leading edge and of the trailing edge, and a continuous decrease in the chord length of the wingtip extension result, and such that the wingtip extension joins the wing in the joint region in an essentially continuous manner.
The literature provides a multitude of different wing tip devices or winglets which are predominantly provided for reducing the aerodynamic drag, and thus for improving aerodynamic performance. The definition of wing tip devices can take place either within the scope of the concept of a new overall aircraft or within the scope of retrofitting such a wing tip device to an already existing aircraft. In the latter case the existing wing geometry is replaced by another wing geometry. In both cases in the design of the wing tip device the resulting gain in aerodynamic performance needs to be balanced against the usually increased structural load, which is often in a simplified manner evaluated by means of the integral wing root bending moment, and all the resulting consequences relating to the weight of the aircraft. The evaluation of various tip devices can return different results based on the given design scenario and on the boundary conditions.
From the general state of the art a so-called wing tip fence (WTF) is also known, which comprises two components of similar size and which extends upwards and downwards almost perpendicularly to the wing. In order to optimise the flow quality at the wing, wing tip devices with continuously smooth transitions of the sweep and the dihedral between the outer part of the main wing on which the wing tip device is arranged and the wing tip device have been implemented.